Will, If you know anyone in the marine business..........You might give this product a test. http://www.owatrol.c...-rustol-owatrol
Below is an excerpt from a post over on Smokstak that describes the use.
<Dear Rick Owatrol is a coating that can be used directly over rusty metal to give it protection from future rust. It is made by a company in Europe and is a marine product. You do have to buff and needlle scale the rusty pieces but once coated it leaves a nice semi gloss coating. I do not know how the color changes with age but will find out in a year or so. It says on the can it can be mixed with most colors but haven't tried to do that because I want the rusty patina on the Cat>
I frequent a UK forum, and a lot of them prefer to keep the patina of the original tractors and that is the product that they all use.